The present invention relates generally to refrigeration systems, and in particular to an absorption type refrigeration system for utilizing solar energy or any other form of energy such as wasted heat from industrial plants.
The absorption type refrigeration system comprises a refrigerant generator, a condenser, an evaporator and an absorber all of which are connected in series in a flow circuit. A solution of a high refrigerant content is heated in the generator by hot water supplied from a reservoir which is connected by recirculation flow path to a solar collector. The fact that solar energy erratically fluctuates with weather and climatic conditions has presented difficulty in designing a system which is required to operate consistently regardless of weather. Backup systems are thus usually required to supply energy to the refrigerant generator when solar energy is insufficient to operate the system satisfactorily. The backup system may take the form of a boiler which is brought into operation while shutting off the solar system whenever the pressure of the vapor phase refrigerant in the generator becomes lower than the pressure at which the refrigerant condenses in the condenser. Therefore, a substantial amount of solar-heated water is left unused in the reservoir even though the generator pressure is only slightly below the condensation pressure. In a prior art system a compressor is employed in the vapor phase refrigerant circuit to supply extra power when the generator pressure is lower than the condensation pressure. When the generator pressure falls below the evaporation pressure the refrigerant is circulated through a flow circuit that bypasses the generator and absorber so that the compressor takes full charge of energy supply. However, since the compressor is provided in the flow circuit of the refrigeration system it tends to contaminate the working fluid with lubrication oil or tends to allow the working fluid to introduce to the internal structure of the compressor.